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MOTOR CONTROL CENTER UNIT WITH RETRACTABLE STAB ASSEMBLY AND METHODS OF
ASSEMBLYING THE SAME

Abstract

A motor control unit (MCU) and methods of operating and assembling the
same are provided. The MCU includes a housing enclosing a retractable
stab assembly (RSA) having stabs attached thereto. The MCU further
includes a bracket assembly having a mount for securing the bracket
assembly to the RSA, guiderails for slideably engaging the RSA to
facilitate the extending and retracting motion, and a lead screw
accessible via an opening in the front of the housing. Rotating the lead
screw causes the RSA to extend and retract which engages and disengages
the stabs. The MCU also includes a motor assembly having a drive motor
coupled to a drive shaft. The motor rotates the shaft in response to
control signals from a remote-device. The motor assembly attaches to the
housing such that the rotation of the shaft in response to the signals
rotates the lead screw to engage and disengage the stabs.

1. A method for assembling a retractable stab assembly for a motor
control unit comprising the steps of: mounting a bracket assembly to a
stab housing having one or more slots for receiving stabs therebetween,
the bracket assembly comprising: a mounting plate having one or more rail
openings and secured to a side of the stab housing opposite the one or
more slots; a rail bracket adapted to attach to a rear of the motor
control unit and having one or more guide rails extending rearwardly
therefrom and at least partially disposed between the one or more rail
openings; and a lead screw bracket defining a first portion having a lead
screw opening and a second portion extending substantially
perpendicularly from the first portion towards the rear of the motor
control unit, the second portion being attached to a side of the mounting
plate opposite the stab housing; and securing a lead screw assembly to
the bracket assembly, the lead screw assembly comprising: a lead screw
having a head and body portion; a nut having an opening for receiving the
lead screw therebetween; and a stopper adapted to interface with the body
portion; wherein the nut is mounted to the first portion of the lead
screw bracket such that the nut opening is aligned with the lead screw
opening; wherein the body portion of the lead screw is inserted through
the lead screw opening and the nut opening and is secured to the second
stopper at an end of the body portion to restrict movement of the lead
screw beyond the stopper; and wherein the lead screw is rotatable such
that rotation of the lead screw shifts the first portion and nut along
the body portion of the lead screw.

2. The method of claim 1, wherein the nut is mounted to a rearward facing
side of the first portion resulting in the head portion being on an
opposite side of the first portion than the nut.

3. The method of claim 1 further comprising the step of: attaching stabs
to the one or more slots in the stab housing.

4. A method for assembling a motor control unit having a housing adapted
to receive one or more electrical components therein, comprising the
steps of: attaching a retractable stab assembly according to claim 1 to a
rear panel of the housing such that attached stabs are positioned to
extend rearwardly from the housing to engage a power source.

5. The method of claim 4, wherein the motor control unit is one of a 12,
18, 24, 30, 36, 42, 48, 54, and 60 inch unit.

6. The method of claim 5, wherein the rear panel for each of the 12, 18,
24, 30, 36, 42, 48, 54, and 60 inch units comprises an opening adapted
for the one or more stabs of the retractable stab assembly to at least
partially extend rearwardly therethrough.

7. The method of claim 6, wherein the opening of each unit is similarly
dimensioned.

8. The method of claim 6, wherein the opening of each unit is differently
dimensioned.

9. The method of claim 4, wherein the nut is mounted to a rearward facing
side of the first portion resulting in the head portion being on an
opposite side of the first portion than the nut.

10. The method of claim 4 further comprising the step of: attaching an
upper panel assembly to an upper part of the housing.

11. The method of claim 10, wherein the upper panel assembly comprises: a
support bracket operatively coupled to an access bracket, wherein the
support bracket is adapted to restrict movement of the motor control
unit, and wherein the access bracket is adapted to restrict movement of
the retractable stab assembly.

12. The method of claim 10 further comprising the step of: attaching a
switch assembly to a front of the housing.

13. The method of claim 12, wherein the switch assembly comprises: a
switch moveable to an on and off position and operatively connected the
support bracket, the access bracket, and the one or more electrical
components in the housing for controlling power flowing to the one or
more electrical components from a power source; and a lead screw access
opening adapted to provide access to the lead screw within the housing.

14. The method of claim 13, wherein access to the lead screw is provided,
via the lead screw access opening, when the switch is in the off
position.

15. The method of claim 13, wherein the access bracket is further adapted
to limits access to the lead screw, via one of the lead screw opening and
the lead screw access opening, when the switch is in the on position.

16. The method of claim 12 further comprising the step of: attaching a
motor assembly to the front of the housing and adjacent to the switch
assembly.

17. The method of claim 16, wherein the motor assembly comprises: a drive
motor coupled to a drive shaft, and wherein the drive shaft extends in a
rearward direction from the motor assembly and through a lead screw
access opening in the front of the housing to engage the lead screw.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of International Application
No. PCT/US2015/19142 filed Mar. 6, 2015, the disclosure of which is
hereby incorporated by reference herein.

TECHNICAL FIELD

[0002] Aspects of the present invention relate generally to motor control
centers (MCC), and more particularly, to MCC subunits, related stab
assemblies, and methods for manufacturing and assembling the same.

BACKGROUND

[0003] A motor control center is a multi-compartment enclosure comprising
a power bus system to distribute electrical power, on a common bus
system, to one or more motor control units within the motor control
center sections. The motor control units are typically constructed to be
removable units that have individual sealed doors on the motor control
center section. These motor control units may contain various motor
control and motor protection components, such as motor controllers,
starters, contactor assemblies, overload relays, circuit breakers, motor
circuit protectors, various disconnects, and similar devices for electric
motors. The motor control units connect to the supply power lines of the
motor control center and supply power to the line side of the motor
control devices, for operation of motors. Motor control centers are
oftentimes used in factories and industrial facilities which utilize high
power electrical motors, pumps, and other loads.

[0004] Typically, when installing or removing motor control units, the
power supply lines are connected. To remove the motor control units, a
door of the motor control unit or motor control center section is opened
and an operator manually pulls the motor control unit to separate the
conductive contacts or stabs from the bus system, thereby disconnecting
the power supply. Installation of a motor control units are accomplished
in a similar manner, whereby the operator manually pushes the bucket into
a compartment of the motor control center section to engage the stabs
with the bus system, thus connecting the system to supply power. In some
instances, the stabs may be difficult to maneuver manually (push and
pull) when an operator is supporting the entire bucket or when the stabs
are not visible. These difficulties may lead to numerous hazards (e.g.,
shocks/misfires, an arc or arc flash) that may be harmful and dangerous
to the operators. It would therefore be desirable to design, manufacture
and assemble a motor control unit that overcomes the aforementioned
difficulties.

SUMMARY

[0005] In an exemplary embodiment, a method for assembling a motor control
unit for a motor control center is provided. The motor control unit
generally includes a housing adapted to receive and/or enclose one or
more electrical components therein. The method comprises the step of
attaching a retractable stab assembly to a rear panel of the housing such
any stabs of the retractable stab assembly are positioned to extend
rearwardly therefrom and from the housing to engage a power source in the
motor control center.

[0006] Assembling the retractable stab assembly includes the steps of
mounting a bracket assembly to a stab housing having one or more slots
for receiving stabs therebetween. The bracket assembly includes a
mounting plate having one or more rail openings and secured to a side of
the stab housing opposite the one or more slots. The bracket assembly
further includes a rail bracket adapted to attach to a rear of the motor
control unit and having one or more guide rails extending rearwardly
therefrom. The guide rails may be at least partially disposed between the
one or more rail openings. The bracket assembly also includes a lead
screw bracket defining a first portion with a lead screw opening, and a
second portion extending substantially perpendicularly from the first
portion towards the rear of the motor control unit. The second portion is
attached to a side of the mounting plate opposite the stab housing.

[0007] Assembling the retractable stab assembly further includes the step
of securing a lead screw assembly to the bracket assembly. The lead screw
assembly includes at least a lead screw having a head and body portion, a
nut having an opening for receiving the lead screw therebetween, and a
stopper adapted to interface with the body portion. The nut may be
mounted to the first portion of the lead screw bracket such that the nut
opening is aligned with the lead screw opening. Additionally, the body
portion of the lead screw is inserted through the lead screw opening and
the nut opening and is secured to the second stopper at an end of the
body portion to restrict movement of the lead screw beyond the stopper.
It should be appreciated that the lead screw is rotatable such that
rotation of the lead screw may shift the first portion and attached nut
along the body portion of the lead screw, e.g., in operation. It should
further be appreciated that the motor control unit may be one of a 12,
18, 24, 30, 36, 42, 48, 54, and 60 inch unit, and that in a further
embodiment, the rear panels of each of the units may include an opening
adapted for the stab assembly and/or one or more stabs of the retractable
stab assembly to at least partially extend rearwardly therethrough. It
should also be appreciated that the openings of each size unit, and more
particularly, the opening of the rear panel, may be similarly
dimensioned, or differently dimensioned.

[0008] In another exemplary embodiment, the method for assembling the
motor control unit further includes the step of attaching an upper panel
assembly to an upper part of the housing, attaching a switch assembly to
a front of the housing, and attaching a motor assembly to the front of
the housing and adjacent to the switch assembly. The switch assembly
includes a switch moveable to an on and off position and operatively
connected the upper assembly, or more particularly, a support and access
bracket of the upper assembly, and the electrical components of the
housing for controlling power flowing to the electrical components from
the power source. Additionally the switch assembly includes a lead screw
access opening adapted to provide access to the lead screw within the
housing. The motor assembly includes a drive motor coupled to a drive
shaft. The drive shaft extends in a rearward direction from the motor
assembly and through a lead screw access opening in the front of the
housing to engage the lead screw.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 illustrates a perspective exploded view of a motor control
center having a motor control unit with retractable stab assembly, in
accordance with the disclosure provided herein;

[0010] FIG. 2 illustrates a perspective view of the motor control unit
with retractable stab assembly, in accordance with the disclosure
provided herein;

[0011] FIG. 3A illustrates a schematic, perspective view of an upper panel
assembly of the motor control unit, in accordance with the disclosure
provided herein;

[0012] FIG. 3B illustrates another schematic, perspective view of the
upper panel assembly of FIG. 3A with an inaccessible lead screw assembly
via the upper panel assembly, in accordance with the disclosure provided
herein;

[0013] FIG. 3C illustrates a further schematic, perspective view of the
upper panel assembly of FIG. 3A with an accessible lead screw assembly,
in accordance with the disclosure provided herein;

[0014] FIG. 3D illustrates yet a further schematic perspective view of the
upper panel assembly of FIG. 3B with a disengaged stab assembly in
accordance with the disclosure provided herein;

[0015] FIG. 4 illustrates a perspective view of the motor control unit
back panel, in accordance with the disclosure provided herein;

[0016] FIG. 5A illustrates a schematic, perspective view, of a lead screw
assembly in an engaged position, in accordance with the disclosure
provided herein;

[0017] FIG. 5B illustrates a schematic, perspective view of the lead screw
assembly of FIG. 5A in a disengaged position, in accordance with the
disclosure provided herein;

[0018] FIG. 6A illustrates a schematic, perspective view of a retractable
stab assembly, in accordance with the disclosure provided herein;

[0020] FIG. 6C illustrates a further schematic, perspective view of the
stab assembly of FIG. 6A;

[0021] FIG. 7A illustrates a perspective view of a shutter assembly in a
closed position, in accordance with the disclosure provided herein;

[0022] FIG. 7B illustrates a perspective view of the shutter assembly of
FIG. 7A in an open position, in accordance with the disclosure provided
herein;

[0023] FIG. 8 illustrates a flow chart for a process of disengaging stabs
of a motor control unit, in accordance with the disclosure provided
herein;

[0024] FIG. 9 illustrates an exemplary embodiment of a remote-controlled
system for operating an embodiment of the motor control unit, in
accordance with the disclosure provided herein;

[0025] FIG. 10 illustrates a perspective view of a motorized control unit,
in accordance with the disclosure provided herein;

[0026] FIG. 11 illustrates a side perspective view of an embodiment of a
motor assembly operatively attached to a motor control unit, in
accordance with the disclosure provided herein;

[0027] FIG. 12 illustrates a side cross-sectional view of an embodiment of
the motorized control unit, in accordance with the disclosure provided
herein;

[0028] FIG. 13 illustrates a side cross-sectional view of a motor
assembly, e.g., of the motorized control unit, in accordance with the
disclosure provided herein;

[0029] FIG. 14 illustrates a rear perspective view of an embodiment of the
motor assembly, in accordance with the disclosure provided herein;

[0030] FIG. 15 illustrates a flow chart for a process of disengaging stabs
of an exemplary embodiment of the motorized control unit, in accordance
with the disclosure provided herein; and

[0031] FIG. 16 illustrates a flow chart for a method of assembling a motor
control unit, in accordance with the disclosure provided herein.

DETAILED DESCRIPTION

[0032] Referring now to the drawings wherein the showings are for purposes
of illustrating embodiments of the subject matter herein only and not for
limiting the same, FIG. 1 illustrates a side perspective view of a motor
control center (MCC) 100. The MCC 100 includes one or more MCC sections
110 configured to house one or more motor control units (MCU) 200. The
MCC section 110 may be generally rectangular in shape, and includes a
plurality of panels arranged to compartmentalize the MCC section 110. For
example, each MCC section 110 may include a pair of opposed side panels
112, a top 114 and bottom panel 116, a back panel 118, and one or more
intermediate panels 120 arranged such that the panels collectively define
one or more openings or compartments 124 adapted for at least partially
receiving the MCU 200 therein.

[0033] In a further embodiment, the MCC section 110 may include a door
panel 122 for encapsulating the MCU 200 within the defined opening of the
MCC section 110. The door panel 122 may be one of the panels of the MCU
200. In an embodiment where multiple MCC sections 110 are provided, one
or more of the above panels may be common between or across the multiple
MCC sections 110. The panels may be constructed from a single piece of
material having a common surface (e.g., sheet metal), or a plurality of
sheets, frames and interlocking assemblies adapted to selectively mount
together for providing a panel-like structure. The frames and
interlocking assemblies may be selectively mounted by a fastening means.
In an exemplary embodiment, the fastening means may be, for example, one
or more screws, nuts and bolts, and rivets applied via mechanical
fastening process through one or more apertures and/or connecting points
of the sheets, frames, and interlocking assemblies. Alternatively, the
fastening means may be applied via a more permanent-like mounting
process, e.g., welding. A combination of both processes may also be used
to achieve the desired arrangement for panels of the MCC section 110, or
for arranging and/or assembling the panels and assemblies described
herein. The MCC section 110 may further include one or more power buses
702 (see FIG. 7A) vertically or horizontally arranged at the rear of the
MCC section 110, at or proximate to the back panel 118. In a further
embodiment, where the one or more power buses 702 is arranged in the back
panel 118, the back panel 118 may be a separate power bus housing 700
(see FIG. 7A) as described herein, which may be operably connected to the
MCC section 110. The power bus 702 is adapted to interface with one or
more components of the MCU 200 for providing power to the same.

[0034] With continued reference to FIG. 1, and now FIG. 2, a perspective
view of an embodiment of the MCU 200 with retractable stab assembly 500
is provided. The MCU 200 comprises a housing 202 shaped for being at
least partially received within the compartment 124 of the MCC section
110. The housing 202 may be made up of one or more panels and/or
assemblies configured for removably securing the MCU 200 within the MCC
section 110, and to partially or fully enclose one or more components
therein. In the embodiment of FIG. 2, the MCU 200 can include a front
panel 210, a back panel 220, a lower panel 230, and an upper panel 240.
Similar to the panels of the MCC section 110, the panels of the MCU 200
may be made from a single piece of material or plurality of frames and/or
interlocking assemblies selectively mounted to one another by the
fastening means discussed herein, or by any means known to persons of
ordinary skill in the art. When assembled, the panels of the housing 202
may define a shape (e.g., generally rectangular) adapted to be removably
secured within the MCC section 110, and to have one or more electrical
components and/or assemblies mounted therein. Examples of electrical
components may include, among other assemblies that will be discussed
below, a contactor or a solid-state motor controller, overload relays to
protect the motor, fuses or a circuit breaker to isolate a motor circuit,
or combinations thereof.

[0035] With continue reference to the figures, the front panel 210 may
include one or more openings arranged in a non-uniform or uniform manner,
and for at least partially receiving therebetween one or more assemblies.
FIG. 2 illustrates a switch assembly opening (not shown) having a switch
assembly 300 at least partially installed therebetween, and a motor
assembly opening (not shown) for receiving, e.g., an embodiment of a
panel assembly 350 partially installed therebetween. Additional openings
may also be provided for at least partially receiving a fastening means
therebetween for selectively mounting the front panel 210 to one or more
of the other panels of the MCU 200. In one embodiment, the openings may
be one or more fastening apertures 216 or recesses extending at least
partially through the front panel 210 for receiving the fastening means,
and arranged to correspond with fastening apertures and/or recesses of
the other panels. The fastening apertures 216 may include a threaded
portion that corresponds to a threaded portion of the fastening means
(e.g., threaded screw).

[0036] In a further embodiment, the front panel 210 may include a lead
screw access opening 218 for providing access to a lead screw assembly
600, for example, when the front panel 210 is in a closed position. In an
exemplary embodiment, the lead screw access opening 218 may be its own
opening in the front panel 210, or in a further embodiment, an opening in
a drive panel 352 of the panel assembly 350. In yet a further embodiment,
the front panel 210 may include an indicator opening 232 for viewing one
or more status indications for the MCU 200, e.g., engaged or disengaged
stabs status, live unit status, lock status etc. Similar to the lead
screw access opening 218, the indicator opening 232 may be its own
opening on the front panel 210, or an opening on one or more assemblies,
e.g., switch assembly 300. The front panel 210 may further include one or
more hinge assemblies 222 for mounting one side of the front panel 210 to
one of the side panels (not shown) of the MCU 200, a structure of the MCC
section 110, or in certain configurations, both.

[0037] As previously disclosed, the drive panel 352 may include one or
more openings for providing access to the lead screw 610. The drive panel
352 may further include additional openings, for example, fastening
apertures for fastening the drive panel 352 to the front panel 210 or
other panels of the MCU 200. The panel assembly 350 may further include
one or more panel covers 354 for covering the openings of the drive panel
352. For example, FIG. 2 shows one panel cover 354 for covering the lead
screw access opening 218. The panel cover 354 may include one or more
openings 356 for at least partially receiving a fastening means
therebetween, and for slideably mounting the panel cover 354 to the drive
panel 352 or front panel 210.

[0038] With continued reference to the figures, the switch assembly 300
may include a switch panel 302 having a switch opening 304 for at least
partially receiving a switch 310 therebetween. The switch panel 302 may
include additional openings similar to the openings of the drive panel
352, e.g., fastening apertures for fastening the switch panel to the
front panel 210, indicator openings 232 or lead screw access openings
218. The switch 310 may be operably connected to a switch control board,
circuit breaker, or the like, having one or more components for powering
on/off one or more electrical components of the MCU 200. For example, as
described herein, in one embodiment, the switch 310 may control the
operability any motor attached to the MCU 200 by controlling limiting
motors ability to rotate the lead screw 610 to extend or retract the stab
assembly 500.

[0039] In a further embodiment, the switch 310 may be operably connected
to one or more components, frames or interlocks in an upper panel
assembly 400 (FIG. 3). In this embodiment, the switch assembly 300 may
include one or more frames or interlocks (not shown) selectively attached
or fastened by a fastening means to one or more frames or interlocks of
the upper panel assembly 400 for shifting the upper panel assembly 400
from a first position to a second position. For example, when the switch
300 is in the live position, access to the lead screw 610 is restricted
with the upper panel assembly 400 in the first position (FIG. 3B),
whereas access to the lead screw 610 is provided with the switch in the
off/dead position and the upper panel assembly 400 in the second position
(FIG. 3C).

[0040] Referring now to FIGS. 3A-3D, an embodiment of the upper panel 240
is provided of the MCU 200 is provided. The upper panel 240 may be formed
from a single-piece of material in one embodiment, e.g., sheet metal, or
in another embodiment, or a combination of both. In an embodiment where
the upper panel 240 is formed from one or more frames and interlocking
assemblies coupled together, the one or more frames and interlocking
assemblies coupled together make up the upper panel assembly 400. The
upper panel assembly 400 may be configured such that at least a portion
thereof is operably moveable from a first position to a second position,
e.g., upwards or downwards. In the embodiment of FIG. 3A, the upper panel
assembly 400 includes a first support bracket 402 comprising a first
portion 404, a second intermediate portion 406, and a third portion 408.
The first portion 404 and third portion 408 are connected via the second
intermediate portion 406, and at least partially extends in a first
direction, e.g., downwardly, beyond the second intermediate portion 406.

[0041] In one embodiment, the first 404, second 406, and third portion 408
may be individual frames or interlocks connected via, for example, a
fastening means as described herein, or in another embodiment, the
portions may be integral formed. In a further embodiment, the portions
may be formed from a single piece of material have one or more bends
(i.e., bent portions) defining the first 404, second 406, and third
portions 408. The first portion 404, second portion 406, and third
portion 408 can further include one or more fastening apertures adapted
to receive a fastening means therebetween for operably coupling the upper
panel assembly 400 to one or more other frames or assemblies of the MCU
200, for example, the switch assembly 300.

[0042] The first portion 404 may further include a first extension 410.
The first extension 410 may be positioned substantially perpendicular to
the first portion 404, such that it extends in a rearward direction from
the first portion 404 towards the back panel 220. The first extension 410
may be formed from the same piece of material as the first portion 404,
or coupled to the first portion 404 by a fastening means. As illustrated
in FIG. 3A, the first extension 410 can be formed from the same piece of
material, and is bent in a substantially rearward direction from the
first portion 404. The first extension 410 may further include a first
restrictor piece 412. The first restrictor piece 412 may extend
substantially perpendicularly to the first extension 410 in an upward
direction e.g., protruding upwardly. As shown exemplarily in FIG. 3A, the
first restrictor piece 412 extends from one side of the first extension
410. The first restrictor piece 412 may be formed from the same piece of
material as the first extension 410, or be coupled to the first extension
410 by a fastening means, or any other means known to persons having
ordinary skill in the art. In an embodiment where the first extension 410
and the first restrictor piece 412 are formed from the same piece of
material, the first restrictor piece 412 may be bent to the desired
substantially perpendicular position. In operation, for example, when the
MCU 200 is live (i.e., the stabs 520 are engaged), the first restrictor
piece 412 may be operably adapted to limit or restrict movement of the
MCU 200 from the MCC section 110.

[0043] The third portion 408 may include a means for accessing a lead
screw 610. As shown in FIG. 3A, the means for accessing the lead screw
can be an access bracket 414 having one or more access bracket openings
416 adapted or sized to provide access to the lead screw 610, or in a
further non-limiting embodiment, for receiving e a lead screw tool (not
shown) for adjusting the lead screw 610 at least partially therebetween.
The access bracket 414 may be made from one or more frames selectively
attached to form the access bracket 414, as shown in FIG. 3A, or the
access bracket 414 may be made from a single piece of material, similar
to the material of the third portion 408. The access bracket 414 may be
selectively attached to the third portion 408 by the fastening means
disclosed herein or by any means known to person of ordinary skill in the
art. Additionally, the access bracket 414 may be integrally formed with
at least a portion of the third portion 408. As used herein, integrally
formed means to couple such that the pieces are relatively permanently
joined. In one embodiment, the access bracket 414 may extend in a
generally downward direction, opposite from the direction of the first
restrictor piece 412. Additionally, the access bracket 414 may be bent
such that at least a portion of the access bracket 414, i.e., a first
bent portion 418, extends in a substantially rearward direction towards
the back panel 220. The access bracket 414 may be bent further, i.e.,
includes a second bend, such that at least a portion of the access
bracket 414 i.e., the second bent portion 420, extends in a substantially
upward, similar to the direction of the first restrictor piece 412. This
second bent portion 420 of the access bracket may be operable to restrict
movement of the stab assembly 500 in instances where the stabs 520 may be
partially engaged.

[0044] In operation, at least a portion of the upper panel assembly 400
(e.g., access bracket 414) can shift in a relatively upwards or downwards
direction for aligning the access bracket opening 416 with the lead screw
access opening 218. Shifting of the access bracket 414 may correspond to
the live/dead status of the MCU 200, i.e., turning on or off the switch
310. For example, when an installed MCU 200 is in the live status, i.e.,
the switch 310 is on, the upper panel assembly 400 may in a first
position to restrict movement of the MCU 200 and limit access to the lead
screw assembly 600. When an operator switches off the switch 310, at
least a portion of the upper panel assembly 400 may shift from a first
position (FIG. 3B) to a second position (FIG. 3C), thereby providing
access to the lead screw assembly 600, and allowing for the MCU 200 to be
removed once the stabs 520 are disengaged.

[0045] Referring to FIG. 4, a perspective view of an embodiment of the
back panel 220 of the MCU 200 is illustrated. The back panel 220 may be
constructed from a material similar to that of the other panels of the
MCU 200, and may include a plurality of openings, e.g., apertures, for
receiving a means for selectively attaching (e.g., the fastening means)
the back panel 220 to one or more of the other panels of the MCU 200. In
the embodiment of FIG. 3, the back panel 220 includes an upper portion
222 and a lower portion 224. The upper portion 222 and lower portion 224
may be formed from a single piece of material, or be formed from multiple
pieces of materials connected to one another by, for example, the
fastening means disclosed herein. In either configuration of the back
panel 220, single or multi-piece construction, the upper portion 222 may
include an opening 226 adapted for at least partially having the stab
assembly 500 extending outward therefrom. In one embodiment, the stab
assembly 500 may be the upper portion 222 of the back panel 220, and may
be selectively fastened to the lower portion 224 by the fastening means
described herein, or by any means known to persons of ordinary skill in
the art and capable of selectively attaching the stab assembly 500 to the
lower portion 224.

[0046] It should be appreciated that the openings 226 defined for the stab
assembly 500 in the MCU 200, or more particularly, the back panel 220,
may be the same size regardless of the size of the MCU 200, e.g., a 12,
18, 24, 30, 36, 42, 48, 54, or 60 inch tall unit, etc. That is, while the
dimensions, e.g., height, width, depth, of the MCU 200 may differ, the
openings 226 for any size MCUs 200 may be the same, which allows for the
modular retractable stab assembly 500 to be mass produced. It should
further be appreciated that the upper panel assembly 400 (FIG. 3A) or
other sub-assembly disclosed herein may also be mass produced to fit any
size MCU 200.

[0047] Referring now to FIGS. 6A-6C, an embodiment of a means for
electrically disconnecting the MCU 200 from one or more power buses 702
in shown. The means for electrically disconnecting the MCU 200, in an
exemplary embodiment, may be the retractable stab assembly 500. The stab
assembly 500 may include a stab housing 510 having one or more openings
or slots 512 adapted to at least partially receive therein or have
attached thereto one or more conductive contacts or stabs 510 (FIG. 6B).
The stab housing 510 may be made from a rigid polymer having electrical
properties, or any material known to persons of ordinary skill in the art
and capable of having one or more stabs 520 fixedly attaching thereto.
The stab housing 510 may be formed from a first housing section 514
having one or more fastening apertures or recesses (not shown) for
removably attaching one or more stabs thereto, and a second housing
section 516 adapted to at least partially mate with the first housing
section 514. The second housing section 516 is the outermost portion of
the stab housing 510, and may be frictionally fitted to the first housing
section 514, or selectively attached thereto via a fastening means. The
second housing section 516 may further include a means for accessing a
power bus.

[0048] The means for accessing a power bus may be a access shoulder 518
extending in a rearward direction from one side of the stab housing 510,
e.g., the second housing section 516 in FIG. 6C, and be adapted to
operatively engage at least a portion of a shutter assembly 710 (FIG. 7A)
for moving one or more shutters of the shutter assembly 710 from a first
closed position (FIG. 7B) to a second open position (FIG. 7A) to allow
for one or more stabs 520 to engage with a corresponding power bus 702.

[0049] Referring now to FIGS. 5A-B, the stab assembly 500 may further
include a lead screw bracket assembly or lead screw bracket 550. In one
embodiment, the lead screw bracket 550 may be a single-piece of material
having one or more bends defining a first portion 552, second portion
554, and third portion 556, selectively coupled to a mounting plate 560.
In a further embodiment, the first 552, second 554, and third portion
556, can be formed from separate pieces selectively attached to one
another by, e.g., a fastening means, or be integrally formed as described
herein.

[0050] In the embodiment of FIG. 5A, the first 552, second 554, and third
portions 556 are formed from a single piece of material bent in a manner
to define the first 552, second 554, and third portions 556. The first
portion 552 may have a length greater than the second 554 and third
portions 556, and may be attached to the mounting plate 560, mounting
bracket 570, or both. The second portion 554 may be disposed between the
first 552 and third portion 556, and includes a lead screw opening 558
adapted for at least partially receiving a lead screw 610 therebetween.
The third portion 556 extends rearwardly from the second portion 554, and
may be arranged substantially parallel to the first portion 552. The
mounting plate 560 may be formed from a similar material to the lead
screw bracket 550, and may include one or more fastening apertures 562
for selectively attaching the mounting plate 560 to the mounting bracket
570. The mounting plate 560 may be attached to the mounting bracket 570
by any of the fastening means described herein, or by other means known
to persons having ordinary skill in the art. In one embodiment, the
mounting plate 560 may have a thickness equal to or greater that the
thickness of the mounting bracket 570, for providing support for the lead
screw support bracket 550. However, it should be appreciated that a
thinner mounting plate 560 may be used depending on engineering
requirements for the MCU 200, and chosen with sound judgment.

[0051] The stab assembly 500 may include one or more guide rail brackets
580 for selectively attaching the stab assembly 500 to the back panel
220, and slideably engaging the mounting bracket 570. In an exemplary
embodiment, the guide rail bracket 580 may include one or more bent
portions defining a guide rail bracket upper portion 582, and a guide
rail bracket lower portion 584. As illustrated in FIG. 5A, the guide rail
bracket upper portion 582 may include a means for slideably engaging one
or more stabs, i.e., one or more guide rails 590 extending rearwardly
therefrom for slideably engaging the mounting bracket 570, and lower
portion 584 may be adapted to interface or be mounted to the back panel
220 for securing the guide rail bracket 580 to the back panel 220. The
guide rails 590 may be generally cylindrical, and adapted to be at least
partially inserted between one or more openings (not shown) of the
mounting bracket 570 for slideably engaging the mounting bracket 570
along the guide rails 590. In the embodiment of FIG. 5A, two guide rail
brackets 580 are shown, with each guide rail bracket 580 having a pair of
guide rails 590 extending rearwardly from a side of the guide rail
brackets 580. The guide rail brackets 580 may include one or more
openings 585 for at least partially receiving a fastening means
therebetween, and for selectively mounting the guide rails 590 to the
guide rail brackets 580. In a further embodiment, the guide rails 590 may
be integral with the guide rail brackets 580, or be formed as a single
piece.

[0052] The guide rails 590 may be selectively attached to the back panel
220 by one or more guide rail holders 592 (FIG. 6B). The guide rail
holders 592 may have one or more bent portions defining at least a holder
first portion 593 and a holder second portion 594. The holder first
portion 593 may include an opening for at least partially receiving the
guide rail 590 therebetween. The guide rail 590 may be selectively
secured to the holder 592 by weld or any other means known to persons of
ordinary skill in the art, and capable of securing the guide rail 590 to
the holder 592. The guide rail holder second portion 594 may be adapted
to interface with the upper portion 222 the back panel 220 to provide
further support for selectively securing the stab assembly 500 to the
back panel 220. In the embodiment of FIG. 6B, each guide rail 590 is
shown having at least one guide rail holder 592 attached thereto for
securing the same to the upper portion 222. It should be appreciated,
that the guide rail holder 592 may be utilized for securing the guide
rail 590, and not for restricting the slideable engagement between the
guide rails 590 and the mounting bracket 570.

[0053] With continue reference to FIG. 5A, an exemplary embodiment of a
lead screw assembly 600 is shown. The lead screw assembly 600 may
comprise a lead screw 610 having a body portion 615 and a head portion,
and one or more nuts or stoppers (630, 632) for limiting axial movement
of the retractable stab assembly 500. The body portion 615 may be any
shape, and have at least a portion thereof threaded for interfacing with
a threaded portion of the stoppers (630, 632). In the embodiment of FIG.
5A, the body portion 615 is generally cylindrical, however, the body
portion 615 may be any polygon shape known in the art. The head 620 may
also be generally cylindrical or any polygon shape, and includes one or
more voids or recesses 622 adapted to interface with a lead screw tool
(not shown) or an actuating device (not shown). As shown in FIG. 5A, the
void 622 defines a first head portion 624 and a second head portion 626.
The void 622 may be non-uniform or uniform around the perimeter of the
head 620, and may be adapted or sized such that at least a portion
thereof is adapted to at least partially receives a portion of a first
lead screw head support bracket 440 and a second lead screw head support
bracket 442 (FIG. 3B) therebetween, for providing support for the lead
screw assembly 600.

[0054] The first 440 and second 442 lead screw head brackets may be part
of the lead screw assembly 600, or as shown in the embodiment of FIG. 3B,
a part of the upper panel assembly 400. The first 440 and second 442 lead
screw head support brackets may include one or openings for operably
connecting to one or more adjacent panels of the MCU 200, or as shown in
FIG. 3D, the upper panel assembly 400. The first lead screw head support
bracket 440 may further include one or more bends defining a first upper
portion 444 and second lower portion 445. The first upper portion 444 may
be adapted to selectively attach the same to a structure in the upper
panel assembly 400, e.g., via a fastening means. The structure may be
moveable or fixed. The second lower portion 445 may be adapted to
selectively attach the same to one or more openings in the second lead
screw head support bracket 442.

[0055] In one embodiment, the first 440 and second 442 lead screw brackets
may include at least a portion thereof having a polygonal or arcuate
profile adapted to interface with the void 622, such that vertical and or
horizontal movement of the head 620 may be limited. Similar to the first
lead screw head support bracket 440, the second lead screw head support
bracket 442 may include one or more bends defining at least a first bend
portion 446 and a second bend portion 447. In the embodiment of FIG. 3C,
the first bend portion 446 may include one or more openings for receiving
a fastening means at least partially therebetween for selectively
attaching the second lead screw head support bracket 442 to the first
lead screw head support bracket 440.

[0056] The second bend portion 447 may further include one or more
openings adapted for receiving a fastening means therebetween, or as
shown in FIG. 3D, at least a portion of an indicator assembly 470
therebetween. Status indicators of the indicator assembly 470 may be
viewed via the indicator opening 232. The indicator assembly 470 may be
formed from a single-piece of material, or be formed from a plurality of
frames selectively attached together by any of the fastening means
described herein. The indicator assembly 470 may include a first
indicator portion 472 having status indications (e.g., live, engaged,
disengaged, dead etc.) for providing the status of the MCU 200, and a
second indicator portion 474 adapted to operationally shift from a first
position to a second position which may correspond with the shifting of
at least a portion of the upper panel assembly 400, e.g., the access
bracket 414.

[0057] The stoppers (630, 632) may be made from a metallic material
similar to that of the lead screw body, or any material known to persons
of ordinary skill in the art and adaptable to restrict movement of the
lead screw 610 and/or stab assembly 500. The stoppers (630, 632) may also
include a threaded portion corresponding with the threaded portion of the
lead screw 610. The first stopper 630 may have a similar configuration to
that of the second stopper 630.

[0058] In the embodiment of FIGS. 5A and 5B, at least one of the stoppers
(630, 632), may be operably adapted to axially shift along the body
portion 615 of the lead screw 610 when the stab assembly 500 shifts from
a first engaged position (see FIG. 5A) to a second disengaged position
(see FIG. 5B). The first stopper 630 and the second 632 may abut one
another when the stab assembly 500 is in the engaged position (FIG. 5A),
and be spaced apart when the stab assembly 500 is in the disengaged
position (FIG. 5B). The first stopper 630 may be selectively mounted to
the second portion 554 of the lead screw support bracket 550, e.g., via
fastening means or welding, such that movement of the stab assembly 500
corresponds with the movement of the first stopper 630 along the axis of
the lead screw. The second stopper may include a restrictor plate 634
mounted at one end of the second stopper 632 to restrict axial movement
of the second stopper 632 along the lead screw 610. For example, the
restrictor plate 634 in FIG. 5B may limit the lead screw 610 from
extending beyond the restrictor plate 634 by not including an opening or
having an opening with a smaller size (e.g., smaller diameter) that the
diameter of the body portion 615.

[0059] Referring now to FIGS. 7A-B, front perspective views of a shutter
assembly 710 are provided. The shutter assembly 710 may include a shutter
plate 712 operably coupled to an access bracket assembly 720. The shutter
plate 712 may include one or more fastening apertures 714 adapted for
slideably mounting the shutter assembly 710 to the power bus housing 700.
In the embodiment shown in FIGS. 7A-B, the shutter plate 712 includes at
least four (4) fastening apertures 714 slideably mounting the shutter
plate 712 to the power bus housing 700. The shutter plate 712 may further
include one or more shields 716 for blocking access to one or more
corresponding power buses 702 within the power bus housing 700 in a first
position, e.g., a closed position. The shutter plate 712 further include
one or more power bus apertures 718 that may be offset from the fastening
apertures 714 for providing access to the power buses 702 in a second
position, e.g., an open position. The power bus apertures 718 may be
generally spaced an equidistance apart, and may be shaped/adapted to at
least partially receive a stab 520 therebetween for interfacing with the
power bus 702.

[0060] With continued reference to FIGS. 7A-B, the access bracket assembly
720 may further include an access bracket panel 722 having one or more
access bracket frame fastening apertures (not shown) for selectively
mounting the access bracket panel 722 to the power bus housing 700, or a
structure proximate to the power bus housing 700. The access bracket
panel 722 may include one or more grooves (not shown) adapted to
slideably engage a means for moving the shutter plate 712 from the first
position to the second position. In one embodiment, the means for moving
the shutter plate 712 may be a biasing member (not shown), for example, a
spring loaded mechanism configured for shifting the shutter plate 712
from the first position to the second position. The access bracket
assembly 720 may further include an extender piece 724 adapted to
interface with at least a portion of the stab assembly 500, e.g., the
access arm or shoulder 518, for moving the shutter plate from a closed
position to an open position when extending the retractable stab assembly
500 towards to the power bus housing 700 for engaging one or more stabs
520 with one or more corresponding power buses 702. In operation, the
interfacing between the access shoulder 518 and the extender piece 724
may cause a spring of the spring mechanism to compress as the shutter
plate 712 moves from the closed position to the open position.

[0061] With reference now to FIG. 8, an embodiment of a method 1000 for
servicing a motor control unit is provided. It should be appreciated that
following steps are not required to be performed in any particular order,
and are hereby provided for exemplary purposes. For example, steps for
disengaging one or more stabs may not be necessary where the stabs were
previously disengaged, and/or where a motor control unit has previously
been removed from its compartment.

[0062] In step 1010, moving the switch 310 from a first on position to a
second off position. In this step, by moving the switch to the off
position, power to one or more electrical components within the motor
control unit may be interrupted. In an exemplary embodiment, moving the
switch 310 to the second position may shift at least a portion of the
upper panel assembly, e.g., the first support bracket 402, in a downwards
direction thereby providing access to the lead screw 610 via the access
bracket 414. In step 1020, disengaging the stabs 520 from the power bus
702. In embodiments where the motor control unit includes fixed stabs,
pulling out the motor control unit via a handle, for example, may
disengage the stabs. In embodiments where the MCU 200 includes the
retractable stab assembly 500, the step of disengaging the stabs may
include the step of: inserting at least a portion of a lead screw tool
into the opening 416, and shifting (e.g., rotating) the lead screw 610
from a first position to a second position, thereby retracting the stab
assembly 500 in a direction towards the front panel 210, and disengaging
the stabs 520 from the power bus 702.

[0063] In step 1030, removing the MCU 200 from the MCC section 110. As
previously described, in embodiments of the motor control units having
fixed stabs, removing the motor control unit may inherently disengage the
stabs. In step 1040, disassembling the stab assembly. In step 1050,
installing the retractable stab assembly 500 in the MCU 200. In step
1060, at least partially inserting the MCU 200 having the retractable
stab assembly 500 into the compartment of the MCC section 110, and
engaging one or more stabs 520 with the power bus 702. In this step,
engaging the one or more stabs may be accomplished by extending the stab
assembly 500 rearwardly by, for example, rotating the lead screw 610 in
an engaging direction.

[0064] With continued reference to the figures and now FIG. 9, an
exemplary embodiment of a remote-controlled system 10 for operating an
embodiment of the MCU 200 is provided. The system 10 may include a
remote-device or pendant 20 operatively connected to one or more
embodiments of a motorized MCU 200, i.e., a motorized control unit 800.
The connection 15 between the pendant 20 and the motorized control unit
800 may be wired, via one or more cables, or wireless, via one or more
wireless transceiver of the motorized control unit 800 and the pendant
20.

[0065] In one embodiment, the pendant 20 may include a memory (not shown)
for storing executable instructions, e.g., instructions to activate and
deactivate the motorized control unit 800, and a processing circuit
operable to execute the stored instructions. The pendant 20 may further
include one or more buttons or control knobs 24 for operating the
motorized control unit 800. In operation, shifting the button or knob 24
may cause the processing circuit to execute instructions corresponding to
the shift, e.g., a shift in the first direction may activate the
motorized control unit 800, while a shift in a second direction may
deactivate the motorized control unit 800. It should be appreciated, that
execution of the instructions may generate control signals which are
transmitted to the motorized control unit 800 for operating the same. The
control signals may be transmitted to the motorized control unit 800 via
one or more cables in a wired connection or via the wireless transceiver
in a wireless network environment. The pendant may further include one or
more indicators 22 for identifying a status of the motorized control
unit, i.e., whether the motorized control unit 800 is active (stabs
engaged) or inactive (stabs disengaged). The pendant 20 may also include
a display 26 for displaying the status of the motorized control unit 800.

[0066] With reference to FIG. 10, an embodiment of the motorized control
unit 800 is provided. The motorized control unit 800 may be similar to
the MCU 200 in that in may include a housing 802 adapted to at least
partially enclose one or more electrical components therein, e.g., the
switch assembly 300, upper panel assembly 400, retractable stab assembly
500, and lead screw assembly 600. In the embodiment of FIG. 10, in
addition to the sub assemblies, the motorized control unit 800 comprise a
motor assembly 900 operatively connected to a front panel of the housing
802.

[0067] The motor assembly 900 may include a drive motor 910 operatively
connected to a drive shaft 920 and power adapter 930. The power adapter
930 may include one or more openings adapted to receive one or more
cables for operating the motor assembly 900. The cables may be cables
operatively connected to the pendant 20 for facilitating the transmission
of the control signals to drive the drive motor 910. Additional cables
may also be operatively connected to the power module 930 for connecting
to a power source for powering the electrical components within a housing
902 of the motor assembly 900, e.g., the drive motor 910. In yet a
further embodiment, the motor assembly 900 may be powered by a battery or
other means for powering a drive motor 910 known to persons of ordinary
skill in the art. In yet a further embodiment, the power adapter 930 may
include a wireless transceiver for facilitating the wireless
communication between the pendant 20 and the motor assembly 900.

[0068] With continued reference to the figures and now FIGS. 11-14, the
drive motor 910 may be operatively connected to the pendant 20 for
receiving control signals for providing a motive force to rotate the
drive shaft 920 in multiple directions to operate the motorized control
unit 800. In an exemplary embodiment, the drive shaft 920 may extend
rearwardly from the housing 902 such that the drive shaft 920 interfaces
with the lead screw 610. In yet a further embodiment, the housing 902 may
include back plate 904 with a drive shaft opening 906 adapted for the
drive shaft 920 to extend at least partially therethrough for interface
with the lead screw 610 when the motor assembly 900 is attached to the
motorized control unit 800. It should be appreciated, in a further
embodiment, that one or more seals or adapters may be provided at the
drive shaft opening 906 for interfacing with or supporting the drive
shaft 920 extending rearwardly therefrom. The housing 902 may further
include one or more mounting brackets 908 disposed on opposite sides of
the housing 902 for selectively attaching the motor assembly 900 to the
front of the housing 802.

[0069] In one embodiment, the mounting brackets 908 may include a recess
having an arcuate profile for interfacing with one or more mounting arm
(not shown) on the front of the housing 802 for attaching the motor
assembly. It should be appreciated that in addition to or in lieu of the
recess, the mounting brackets 908 may further include an aperture or hole
for receiving fasteners for securing the motor assembly 900 to the
housing 802, via a corresponding aperture adapted for receiving the
fasteners. In yet a further embodiment, the mounting brackets 908 may be
attached to or integrally formed with the back plate 904 for attaching
the motor assembly 900 to the motorized control unit 800. A handle 940
may also be provided at an upper portion of the housing 902 for
facilitating the attaching and removal of the motor assembly 900 from the
housing 802.

[0070] In yet a further embodiment, the operability of the motor assembly
900 may correspond with the functionality of the switch assembly 300, and
more particularly, the switch 310, and e.g., whether or not it is in an
on or off position. For example, in one exemplary embodiment, an operator
may not be able to switch the switch assembly 300 on unless the
retractable stab assembly is fully retracted or extended. Additionally,
the switch 310 may also not be moveable to the on position if the lead
screw 610 is being rotated, e.g., by the drive shaft or any external
tool. In yet a further exemplary embodiment, no access to the lead screw
access opening 218 may be provided if the switch is in the on position,
thus the motor assembly 900 may not be able to attach to the front of the
housing 802 because the drive shaft 920 may not have access to the lead
screw 610 with a closed/blocked lead screw access opening 218.

[0071] With continued reference to the figures, the drive shaft 920 may
extend rearwardly beyond the back of the housing 902 or back plate 904 to
allow for the drive shaft 920 to be at least partially inserted into the
lead screw access opening 218. Once the drive shaft is inserted into the
lead screw access opening 218, the drive shaft may interface or engage
the lead screw 610 such that rotation of the drive shaft 920, via the
drive motor 910, causes the lead screw 610 to rotate, which extends and
retracts the retractable stab assembly 500 to engage and disengage the
stabs. In yet a further embodiment, the drive shaft 920 may be used in
lieu of the lead screw 610 in that the drive shaft 920 may extend at
least partially through the lead screw opening 558 for attaching the
extended drive shaft 920 to the stoppers 630, 632, for limiting axial
movement of the retractable stab assembly 500 in operation.

[0072] With reference now to FIG. 15, a flow chart for a method 1500 of
disengaging stabs of an exemplary embodiment of the motorized control
unit is provided. It should be appreciated that following steps are not
required to be performed in any particular order, and are hereby provided
for exemplary purposes.

[0073] In step 1510, the drive motor 910 is initiated, via the pendant 20,
to engage the stabs of the retractable stab assembly 500. It should be
appreciated that if the motor assembly 900 has not been previously
attached to the motorized control unit 800, or more particularly the
housing 802, an operator may attach the motor assembly 900, e.g., using
the handle 940, to the housing 802 prior to initiating the drive motor
910. It should further be appreciated, as described herein, that before
attaching the motor assembly 900, the motorized control unit 800 switch
310 should be in the off position, which allows for the drive shaft 920
to extend through the lead screw access opening 218 to engage the lead
screw 610. Upon attaching the motor assembly 900, the operator may
initiate the drive motor 910 by selecting a button or shifting the knob
24 in a first direction to extend the retractable stab assembly 500
rearwardly towards the power bus 702 to engage the stabs with the power
bus 702. Shifting the knob 24 may cause the processing circuit of the
pendant 20 to execute instructions for rotating the drive shaft 920 and
to generate control signals corresponding to the instructions. The
control signals may then be transmitted to the motor assembly 900, or
more particularly the drive motor 910, from the pendant 20, which rotates
the drive shaft 920 in a first direction to engage the stabs with the
power bus 702. In this embodiment, rotation of the drive shaft 920 causes
the lead screw 610 to rotate, which results in the retractable stab
assembly 500 shifting along the guide rails 590 in a direction to engage
the stabs.

[0074] Once the stabs are engaged, in step 1520, a confirmation of the
successful engagement may be transmitted from the motorized control unit
800 to the pendant 20 and displayed, e.g., on the display 26. The
successful engagement/connection confirmation from the motor assembly 900
may be based on or results from, e.g., the lead screw 610 no longer being
rotated in the engaging direction, i.e., the lead screw 610 has stop
rotating in a direction extending the retractable stab assembly 500
towards the power bus 702. It should also be appreciated that the lead
screw 610 no longer rotating in the disengaging direction may be
indicative of the retractable stab assembly being in the fully retracted
position and the stabs being disengaged from the power bus 702. It should
further be appreciated that other circuitry may be provided and activated
upon the retractable stab assembly 500 being in a fully extended and
engaged position, or fully retracted and disengaged position. The
circuitry may then transmit this information, i.e., the assembly is fully
extended, as an engagement signal to the connected pendant 20 for
engagement confirmations, and as a disengagement signal for disengagement
confirmations.

[0075] In step 1530, the operator may then remove the motor assembly 900,
e.g., via the handle 940, from the motorized control unit 800, or more
particularly, the housing 802, and upon receiving the engagement signal
from the motorized control unit 800 or motor assembly 900. In a further
embodiment, to disengage the motorized control unit 800, in step 1540,
the operator may switch the switch 310 to the off position, which
provides access to the lead screw 610, via the lead screw access opening
218 being available with the switch 310 in the off position. The operator
may then attach the motor assembly 900 to the housing 802 such that the
drive shaft 920 extends through the lead screw access opening 218 and
interfaces with the lead screw 610. The operator may then begin
retracting the retractable stab assembly 500 to disengage the stabs from
the power bus 702. To begin retracting the stab assembly 500, the
operator may select a button or shift the knob 24 which may generate and
transmit a disengage control signal from the pendant 20 to the motor
assembly 900 which causes the drive motor 910 to rotate the lead screw
610, e.g., by way of the drive shaft 920, in a direction opposite the
engagement direction or a further direction, which retracts the
retractable stab assembly 500 away from the power bus 702 along an axis
of the guiderails.

[0076] It should be appreciated that one button or knob 24 may be used on
the pendant 20 for extending or retracting the retractable stab assembly
500. It should further be appreciated that a further signal may be
transmitted from the motorized control unit 800 or motor assembly 900 to
the pendant 20 identifying that the motorized control unit 800 is
disengaged, i.e., the disconnection between the stabs and the power bus
702 is complete. Once the stabs have been disengaged from the power bus
700, the motor assembly 900 may be removed from the motorized control
unit 800, via the handle 940.

[0077] With reference now to FIG. 16, an embodiment of a method 1600 for
assembling an embodiment of the MCU 200 is provided. The modularity of
the sub-assemblies, e.g., the upper panel assembly 400, retractable stab
assembly 500, etc., allows for the sub-assemblies to fit any size/type
MCU 200 or motorized control unit 800. This versatility allows for these
sub-assemblies to be mass produced for any embodiment of the control
units described herein.

[0078] In step 1610, the method 1600 includes the step of: selectively
attaching an embodiment of the retractable stab assembly 500 to a rear of
the MCU 200 such that the stab assembly 500 and/or one or more stabs
extending therefrom, are positioned to extend in a rearward direction
from the housing or an opening in the housing to engage a power source,
e.g., power bus 702. In this step, as described herein, the retractable
stab assembly 500 may be secured to a rear panel or other structure in
the MCU 200 such that the stabs may extend rearwardly to engage the power
source. One or more fasteners may be used to secure the stab assembly 500
and/or any of the other sub-assemblies in the MCU 200. In step 1620, the
method 1600 may include the step of: selectively attaching an upper panel
assembly 400 to an upper part of the housing, the upper panel assembly
400 including an access bracket for limiting access to a lead screw; and
a support bracket coupled to the access bracket and adapted to restrict
removal of the motor control unit.

[0079] With continued reference to the figures, in step 1630, the method
1600 may include the step of: selectively attaching a switch assembly 300
to a front of the housing, the switch assembly 300 including a switch
moveable to an on and off position and operatively connected to the upper
panel assembly 400, e.g., one of the support and access bracket, and any
electrical components within the housing. In step 1640, the method 1600
may also include the step of: selectively attaching a motor assembly 900
to the front of the housing and adjacent the switch assembly 300, the
motor assembly 900 including a drive motor 910 coupled to a drive shaft
920, wherein the drive shaft 920 extends in a rearward direction from the
motor assembly 900 and through an opening in the access bracket for
engaging the lead screw, e.g., when the switch is in the off position.

[0080] While specific embodiments have been described in detail, those
with ordinary skill in the art will appreciate that various modifications
and alternative to those details could be developed in light of the
overall teachings of the disclosure. For example, elements described in
association with different embodiments may be combined. Accordingly, the
particular arrangements disclosed are meant to be illustrative only and
should not be construed as limiting the scope of the claims or
disclosure, which are to be given the full breadth of the appended
claims, and any and all equivalents thereof. It should be noted that the
terms "comprising", "including", and "having", are open-ended and does
not exclude other elements or steps; and the use of articles "a" or "an"
does not exclude a plurality.